More than 24 hours after police found Las Vegas gunman Stephen Paddock dead in his hotel room, police have not established a motivate for the deadliest mass shooting in modern US history.

While police and media investigations have started to surface a picture of Paddock — who friends, family, and authorities said was an occasional gambler who enjoyed hunting and aviation — nobody close to or studying Paddock has any idea why he carried out the act.

Paddock, 64, was a millionaire who made much of his money investing in real estate, his brother said. Both his age and supposed income would go against the typical profile of a mass shooter.

Paddock’s brother said in a televised interview that Paddock was “not an avid gun guy,” but he said he did not speak to him often. In the end, police recovered 42 total guns from Paddock’s hotel and home.

While Paddock’s father was a bank robber, a one-time armed and dangerous fugitive, and a diagnosed psychopath, according to the FBI, the elder Paddock was arrested for his crimes when Paddock was just 7 years old.

Clint Van Zandt, a supervisor in the FBI’s behavioural science unit, said he came up empty when looking into Paddock.

“My challenge is, I don’t see any of the classic indicators, so far, that would suggest, ‘OK, he’s on the road either to suicide or homicide or both,” Van Zandt told The Associated Press.

“He knew what he wanted to do. He knew how he was going to do it, and it doesn’t seem like he had any kind of escape plan at all.”

Paddock had no known mental illnesses. He checked into his hotel room three days before opening fire during the last act of the last night of the Route 91 Harvest Festival. The room he picked gave him a good vantage point over the 22,000 concertgoers across the street.